The document analyzes the performance of the Hybrid Efficient and Reliable MAC (HER-MAC) protocol in Vehicular Ad Hoc Networks (VANETs) under non-saturated conditions. It develops 1-D and 2-D Markov chain models to evaluate the packet delivery ratio of safety and non-safety applications respectively. The models consider elements like backoff freezing timer, backoff stages, and short retry limit to better accommodate IEEE 802.11p specifications and provide more accurate estimations of channel access and packet delivery ratio. Simulation results validate the analytical models and show their performance outperforms existing models, especially in terms of packet delivery ratio under different numbers of vehicles and contention windows.
Elastic hybrid MAC protocol for wireless sensor networks IJECEIAES
The future is moving towards offering multiples services based on the same technology. Then, billions of sensors will be needed to satisfy the diversity of these services. Such considerable amount of connected devices must insure efficient data transmission for diverse applications. Wireless sensor network (WSN) represents the most preferred technology for the majority of applications. Researches in medium access control (MAC) mechanism have been of significant impact to the application growth because the MAC layer plays a major role in resource allocation in WSNs. We propose to enhance a MAC protocol of WSN to overcome traffic changes constraints. To achieve focused goal, we use elastic hybrid MAC scheme. The main interest of the developed MAC protocol is to design a medium access scheme that respect different quality of services (QoS) parameters needed by various established traffic. Simulation results show good improvement in measured parameters compared to typical protocol.
Vehicular adhoc network (VANET) adopts or resembles a similar structure of Mobile adhoc network (MANET). The communication in VANET are generally classified into following three categories such as Vehicle to Infrastructure (V2I), Vehicle to Vehicle (V2V) and Hybrid network which is a combination of V2V and V2I network. VANET using the IEEE 802.11p standard has great potential of achieving objectives of Smart intelligent transport system (SITS) for improving transport and road safety efficiency. As more and more services is been provided for V2V based VANET network. It is a challenging task to provide QoS to end user, due to wireless medium that has limited channel availability for transmission. To guarantee QoS and provide efficient network performance, a prioritized MAC need to be designed. Many priority based MAC has been designed in recent times to improve the quality of data delivery to end user. However these do not consider the impact of environment and presence of obstacle which affects the signal attenuation at the receiver end and affecting the QoS of channel availability. To address, this work present an obstacle based radio propagation model, obstacle based CEV (City, Expressway and Village) environmental model and a selective MAC to provide QoS for different services. The proposed model efficiency is evaluated in term of throughput achieved per channel, Collison and success packet transmission. To evaluate the adaptive performance of proposed AMACexperiment are conducted under CEV environment and are compared with existing MAC NCCMA. The outcome achieved shows that the proposed model is efficient in term of reducing Collison, improving packet transmission and throughput performance considering two types of services.
A MAC PROTOCOL WITH DYNAMIC ALLOCATION OF TIME SLOTS BASED ON TRAFFIC PRIORIT...ijaia
In a wireless body area network (WBAN), wireless biomedical sensors are placed around, on, or inside the human body. Given specific requirements, WBANs can significantly improve healthcare, diagnostic monitoring, and other medical services. However, the existing standards such as IEEE 802.11 and IEEE 802.15.4 have some limitations to meet all the requirements of WBANs. Many medium access control (MAC) protocols have been studied so far, most of which are derived from the IEEE 802.15.4 superframe structure with some improvements and adjustments. However, the MAC protocols do not provide the required quality of service (QoS) for various types of traffic in a WBAN. In this paper, a traffic-aware MAC (TA-MAC) protocol for WBANs is proposed, in which time slots are dynamically allocated on the basis of traffic priority, providing the required QoS. According to the performance evaluation results, the proposed TA-MAC is better than IEEE 802.15.4 MAC and the conventional priority-based MAC in terms of transmission time, system throughput, energy efficiency, and collision ratio.
Performance of Vehicle-to-Vehicle Communication using IEEE 802.11p in Vehicul...IJNSA Journal
Traffic safety applications using vehicle-to-vehicle (V2V) communication is an emerging and promising area within the ITS environment. Many of these applications require real-time communication with high reliability. To meet a real-time deadline, timely and predictable access to the channel is paramount. The medium access method used in 802.11p, CSMA with collision avoidance, does not guarantee channel
access before a finite deadline. The well-known property of CSMA is undesirable for critical communications scenarios. The simulation results reveal that a specific vehicle is forced to drop over 80% of its packets because no channel access was possible before the next message was generated. To overcome this problem, we propose to use STDMA for real-time data traffic between vehicles. The realtime properties of STDMA are investigated by means of the highway road simulation scenario, with promising results.
DYNAMIC CURATIVE MECHANISM FOR GEOGRAPHIC ROUTING IN WIRELESS MULTIMEDIA SENS...csandit
Maintaining network stability and extending network lifetime to cope with breaking links and topology changes remain nowadays a unsolved issues in Wireless Multimedia Sensor Networks (WMSNs), which aim to ensure flow delivery while guaranteeing QoS requirements, particularly, during data transmission phase. Therefore, in this paper, we jointly consider multipath transmission, load balancing and fault tolerance, to enhance the reliability of transmitted data. We propose a Dynamic Curative Mechanism for Geographic Routing in WMSNs. Theoricals results and those obtained from simulation study demonstrate the validity and efficiency of our proposed mechanism, and indicate that it is highly advised for multimedia transmission and network stability
In Wireless Sensor Network (WSN), QoS (Quality of Service) in sensor application plays a very important
role. QoS based routing is required to ensure the best use of nodes in WSN. In this paper, a comparative
study of QoS based routing in Media Access Control (MAC) protocols are presented based on the traits to
solve problems like prioritization, timeliness, reliability etc. The study mainly focuses on some priority
based QoS protocols used in WSN and a comparison among them. The study reveals that among the five
mentioned protocols; QMAC, PRIMA, DB-MAC, RAP, GTS; PRIMA shows the best performance in the
category of Packet Prioritization, Scheduling Scheme, Queue Type, Energy Awareness and QoS.
Elastic hybrid MAC protocol for wireless sensor networks IJECEIAES
The future is moving towards offering multiples services based on the same technology. Then, billions of sensors will be needed to satisfy the diversity of these services. Such considerable amount of connected devices must insure efficient data transmission for diverse applications. Wireless sensor network (WSN) represents the most preferred technology for the majority of applications. Researches in medium access control (MAC) mechanism have been of significant impact to the application growth because the MAC layer plays a major role in resource allocation in WSNs. We propose to enhance a MAC protocol of WSN to overcome traffic changes constraints. To achieve focused goal, we use elastic hybrid MAC scheme. The main interest of the developed MAC protocol is to design a medium access scheme that respect different quality of services (QoS) parameters needed by various established traffic. Simulation results show good improvement in measured parameters compared to typical protocol.
Vehicular adhoc network (VANET) adopts or resembles a similar structure of Mobile adhoc network (MANET). The communication in VANET are generally classified into following three categories such as Vehicle to Infrastructure (V2I), Vehicle to Vehicle (V2V) and Hybrid network which is a combination of V2V and V2I network. VANET using the IEEE 802.11p standard has great potential of achieving objectives of Smart intelligent transport system (SITS) for improving transport and road safety efficiency. As more and more services is been provided for V2V based VANET network. It is a challenging task to provide QoS to end user, due to wireless medium that has limited channel availability for transmission. To guarantee QoS and provide efficient network performance, a prioritized MAC need to be designed. Many priority based MAC has been designed in recent times to improve the quality of data delivery to end user. However these do not consider the impact of environment and presence of obstacle which affects the signal attenuation at the receiver end and affecting the QoS of channel availability. To address, this work present an obstacle based radio propagation model, obstacle based CEV (City, Expressway and Village) environmental model and a selective MAC to provide QoS for different services. The proposed model efficiency is evaluated in term of throughput achieved per channel, Collison and success packet transmission. To evaluate the adaptive performance of proposed AMACexperiment are conducted under CEV environment and are compared with existing MAC NCCMA. The outcome achieved shows that the proposed model is efficient in term of reducing Collison, improving packet transmission and throughput performance considering two types of services.
A MAC PROTOCOL WITH DYNAMIC ALLOCATION OF TIME SLOTS BASED ON TRAFFIC PRIORIT...ijaia
In a wireless body area network (WBAN), wireless biomedical sensors are placed around, on, or inside the human body. Given specific requirements, WBANs can significantly improve healthcare, diagnostic monitoring, and other medical services. However, the existing standards such as IEEE 802.11 and IEEE 802.15.4 have some limitations to meet all the requirements of WBANs. Many medium access control (MAC) protocols have been studied so far, most of which are derived from the IEEE 802.15.4 superframe structure with some improvements and adjustments. However, the MAC protocols do not provide the required quality of service (QoS) for various types of traffic in a WBAN. In this paper, a traffic-aware MAC (TA-MAC) protocol for WBANs is proposed, in which time slots are dynamically allocated on the basis of traffic priority, providing the required QoS. According to the performance evaluation results, the proposed TA-MAC is better than IEEE 802.15.4 MAC and the conventional priority-based MAC in terms of transmission time, system throughput, energy efficiency, and collision ratio.
Performance of Vehicle-to-Vehicle Communication using IEEE 802.11p in Vehicul...IJNSA Journal
Traffic safety applications using vehicle-to-vehicle (V2V) communication is an emerging and promising area within the ITS environment. Many of these applications require real-time communication with high reliability. To meet a real-time deadline, timely and predictable access to the channel is paramount. The medium access method used in 802.11p, CSMA with collision avoidance, does not guarantee channel
access before a finite deadline. The well-known property of CSMA is undesirable for critical communications scenarios. The simulation results reveal that a specific vehicle is forced to drop over 80% of its packets because no channel access was possible before the next message was generated. To overcome this problem, we propose to use STDMA for real-time data traffic between vehicles. The realtime properties of STDMA are investigated by means of the highway road simulation scenario, with promising results.
DYNAMIC CURATIVE MECHANISM FOR GEOGRAPHIC ROUTING IN WIRELESS MULTIMEDIA SENS...csandit
Maintaining network stability and extending network lifetime to cope with breaking links and topology changes remain nowadays a unsolved issues in Wireless Multimedia Sensor Networks (WMSNs), which aim to ensure flow delivery while guaranteeing QoS requirements, particularly, during data transmission phase. Therefore, in this paper, we jointly consider multipath transmission, load balancing and fault tolerance, to enhance the reliability of transmitted data. We propose a Dynamic Curative Mechanism for Geographic Routing in WMSNs. Theoricals results and those obtained from simulation study demonstrate the validity and efficiency of our proposed mechanism, and indicate that it is highly advised for multimedia transmission and network stability
In Wireless Sensor Network (WSN), QoS (Quality of Service) in sensor application plays a very important
role. QoS based routing is required to ensure the best use of nodes in WSN. In this paper, a comparative
study of QoS based routing in Media Access Control (MAC) protocols are presented based on the traits to
solve problems like prioritization, timeliness, reliability etc. The study mainly focuses on some priority
based QoS protocols used in WSN and a comparison among them. The study reveals that among the five
mentioned protocols; QMAC, PRIMA, DB-MAC, RAP, GTS; PRIMA shows the best performance in the
category of Packet Prioritization, Scheduling Scheme, Queue Type, Energy Awareness and QoS.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
General Model for Single and Multiple Channels WLANs with Quality of Service ...ijwmn
In this paper we develop an intergraded model for request mechanism and data transmission in the uplink phase in the presence of channel noise. This model supports quality of service. The wireless channel is prone to many impairments. Thus, certain techniques have to be developed to deliver data to the receiver. We calculated the performance parameters for single and multichannel wireless networks, like the requests throughput, data throughput and the requests acceptance probability and data acceptance probability. The proposed model is general model since it can be applied to different wireless networks such as IEEE802.11a, IEEE802.16e, CDMA operated networks and Hiperlan\2.
Channel Aware Mac Protocol for Maximizing Throughput and FairnessIJORCS
The proper channel utilization and the queue length aware routing protocol is a challenging task in MANET. To overcome this drawback we are extending the previous work by improving the MAC protocol to maximize the Throughput and Fairness. In this work we are estimating the channel condition and Contention for a channel aware packet scheduling and the queue length is also calculated for the routing protocol which is aware of the queue length. The channel is scheduled based on the channel condition and the routing is carried out by considering the queue length. This queue length will provide a measurement of traffic load at the mobile node itself. Depending upon this load the node with the lesser load will be selected for the routing; this will effectively balance the load and improve the throughput of the ad hoc network.
Impact of Randomness on MAC Layer Schedulers over High Speed Wireless Campus ...ijcsse
IEEE802.11e standard provides an EDCA mechanism to ensure the QoS using service differentiation function for IMM traffics through the WCN. In an EDCA mechanism, IMM traffics have been classified into four categories and each category has specific priority. Many EDCA schedulers allow these traffics to access the channel based on assigned priorities. The IMM high priority traffic is high delay sensitive and required high bandwidth to ensure QoS over the networks. Scheduling mechanism is the effective way to satisfy IMM traffic but it cannot give guarantee because of the randomness of some EDCA schedulers or proposed networks. In order to provide the QoS, scheduling mechanism is the challenging issue to transmit IMM traffic through the channel and it is still need to be solved over WCN. This work aims to examine the effect of the randomness on different MAC layer schedulers' performance and evaluates the performance of the proposed schedulers using different performance metrics in WCN.
New adaptation method based on cross layer and TCP over protocols to improve ...IJECEIAES
Due to rapid growth of multimedia traffic used over the mobile ad-hoc networks (MANETs), to keep up with the progress of this constraint MANETs protocols becoming increasingly concerned with the quality of service. In view of the random mobility nodes in MANET, TCP becomes more unreliability in case of higher energy consumption and packet loss. In this paper we proposed a new optimization approach to enhance decision making of TCP based on some changes of IEEE 802.11 MAC uses cross layer approach. The aim is to minimize the impact of retransmissions of packet lost and energy consumption in order to analyse and chose the appropriate routing protocol for TCP that can be enhance QoS MANET. Our simulation results based QoS study using NS3 show that, our proposal achieved better performance of TCP in MANETs significantly, and also improved the throughput, energy consumption and facilitates the traffic transmission over routing protocol.
ON DEMAND CHANNEL ASSIGNMENT METHOD FOR CHANNEL DIVERSITY (ODCAM)ijwmn
The IEEE 802.11s Wireless Mesh Networks (WMN) is a new multi-hop technology increasing the coverage
of IEEE 802.11 Wireless Network and providing Internet access. In order to increase the mesh network
capacity, the WMN has evolved from single-radio single-channel architecture to Multi-Channel Multi-
Radios (MC-MR) architecture. In MC-MR the main challenge of the WMN is the channel assignment. In
this article, we propose a new channel assignment method based on channel diversity. This new method
named ODCAM (On Demand channel Assignment Method for channel diversity ) defines a channel
diversity mechanism used to select a new channel along the path between the source and the destination.
The best path between the source and the destination is provided by the HWMP (Hybrid Wireless Mesh
Protocol) protocol using MWCETT (Modified Weighted Cumulative Expected Transmission Time) an
extension of the WCETT metric. The simulation results show the ODCAM performance compared with an
hybrid approach.
Effect of Interleaved FEC Code on Wavelet Based MC-CDMA System with Alamouti ...IJCSEIT Journal
In this paper, the impact of Forward Error Correction (FEC) code namely Trellis code with interleaver on
the performance of wavelet based MC-CDMA wireless communication system with the implementation of
Alamouti antenna diversity scheme has been investigated in terms of Bit Error Rate (BER) as a function of
Signal-to-Noise Ratio (SNR) per bit. Simulation of the system under proposed study has been done in M-ary
modulation schemes (MPSK, MQAM and DPSK) over AWGN and Rayleigh fading channel incorporating
Walsh Hadamard code as orthogonal spreading code to discriminate the message signal for individual
user. It is observed via computer simulation that the performance of the interleaved coded based proposed
system outperforms than that of the uncoded system in all modulation schemes over Rayleigh fading
channel.
Handover Behaviour of Transparent Relay in WiMAX NetworksIDES Editor
The knowledge on handover behaviour in WiMAX
network is essential for network management and planning
in order to achieve optimum system throughput. In this paper
we have analysed the handover behaviour of transparent relay
in several configurations for the IEEE 802.16j Mobile Multihop
Relay (MMR) WiMAX network. The simulation was
performed using NCTUns tool and adopted the hard handover
mechanism for three different relay network topologies with
varying mobile station speeds. The result shows the handover
for internal network is faster than the external network and
by appropriate relay deployment the system throughput can
be increased up to 14.39%.
ACHIEVING ENHANCED THROUGHPUT IN MOBILE ADHOC NETWORK USING COLLISION AWARE M...ijasuc
Since wireless medium is high demand resource the design of an efficient medium access protocol is
important for Mobile Adhoc Networks. As MAC is the base layer in the protocol stack a performance gain
in this layer will have significant improvement in the overall performance of the network. Since the current
IEEE 802.11 MAC standard is not adaptive to the network scenario its performance is poor in terms of
throughput, fairness and delay. Although several alternatives to the existing standard is proposed many of
them are not satisfactorily address the key issues of keeping the simplicity of the protocol and avoiding the
overhead on the nodes on duty in emergency situations where usually adhoc networks are applied. In this
paper we propose an adaptive, collision aware MAC protocol for wireless adhoc networks, termed the
Collision Based Contention (CBC) protocol, in which depends on the current collision level on the shared
medium contending nodes dynamically decides its Backoff value to avoid a blind random waiting before
access to the medium. The CBC scheme outperforms the BEB scheme employed in the IEEE 802.11 MAC
standard and other competing proposals.
Joint Routing and Congestion Control in Multipath Channel based on Signal to ...IJECEIAES
Routing protocol and congestion control in Transmission Control Protocol (TCP) have important roles in wireless mobile network performance. In wireless communication, the stability of the path and successful data transmission will be influenced by the channel condition. This channel condition constraints come from path loss and the multipath channel fading. With these constraints, the algorithm in the routing protocol and congestion control is confronted with the uncertainty of connection quality and probability of successful packet transmission, respectively. It is important to investigate the reliability and robustness of routing protocol and congestion control algorithms in dealing with such situation. In this paper, we develop a detailed approach and analytical throughput performance with a cross layer scheme (CLS) between routing and congestion control mechanism based on signal to noise ratio (SNR) in Rician and Rayleigh as multipath fading channel. We proposed joint routing and congestion control TCP with a cross layer scheme model based on SNR (RTCP-SNR). We compare the performance of RTCP-SNR with conventional routing-TCP and routing-TCP that used CLS with routing aware (RTCP-RA) model. The analyses and the simulation results showed that RTCP-SNR in a multipath channel outperforms conventional routing-TCP and RTCP-RA.
F-802.11P: A Fuzzy Enhancement for IEEE 802.11P in Vehicle-to-Everything Comm...IJCNCJournal
Vehicle-to-Everything communications (V2X) are becoming increasingly popular as a solution for safer roads and better traffic management. One of the essential protocols in V2X is the Dedicated Short Range Communication (DSRC) protocol suite. DSRC includes the IEEE 802.11p protocol that operates at the medium access control (MAC) and physical (PHY) layers. Upon collision, the IEEE 802.11p MAC layer applies a carrier sense multiple access/collision avoidance (CSMA/CA) mechanism that randomly selects a backoff time to re-check the channel activity and then retransmit. However, the random selection of the backoff time may lead to further packet collisions that decrease the utilization of the communication channel, which suffers from a limited bandwidth in the first place. This paper proposes a fuzzy model based on rational decision-making, which we call F-802.11p, to improve the IEEE 802.11p protocol backoff time selection by limiting the IEEE 802.11p beacon messages to better use of the available bandwidth. A simulation study presents the evaluation of our work compared to IEEE 802.11p. We deployed the simulation software in two scenarios: the Veins Framework map and the map of New Administrative Cairo in Egypt. We base our comparison on slots backoff, times into backoff, PHY busy time, MAC busy time, total lost packets, and generated/received beacon messages. Simulation results show that both protocols have comparable results in slots backoff, times into back off, and the generated beacon messages. At the same time, our F-802.11p significantly outperforms the IEEE 802.11p in PHY busy time, MAC busy time, total lost packets, and the received beacon messages in both scenarios.
F-802.11P: A FUZZY ENHANCEMENT FOR IEEE 802.11P IN VEHICLE-TO-EVERYTHING COMM...IJCNCJournal
Vehicle-to-Everything communications (V2X) are becoming increasingly popular as a solution for safer
roads and better traffic management. One of the essential protocols in V2X is the Dedicated Short Range
Communication (DSRC) protocol suite. DSRC includes the IEEE 802.11p protocol that operates at the
medium access control (MAC) and physical (PHY) layers. Upon collision, the IEEE 802.11p MAC layer
applies a carrier sense multiple access/collision avoidance (CSMA/CA) mechanism that randomly selects a
backoff time to re-check the channel activity and then retransmit. However, the random selection of the
backoff time may lead to further packet collisions that decrease the utilization of the communication
channel, which suffers from a limited bandwidth in the first place. This paper proposes a fuzzy model based
on rational decision-making, which we call F-802.11p, to improve the IEEE 802.11p protocol backoff time
selection by limiting the IEEE 802.11p beacon messages to better use of the available bandwidth. A
simulation study presents the evaluation of our work compared to IEEE 802.11p. We deployed the
simulation software in two scenarios: the Veins Framework map and the map of New Administrative Cairo
in Egypt. We base our comparison on slots backoff, times into backoff, PHY busy time, MAC busy time,
total lost packets, and generated/received beacon messages. Simulation results show that both protocols
have comparable results in slots backoff, times into back off, and the generated beacon messages. At the
same time, our F-802.11p significantly outperforms the IEEE 802.11p in PHY busy time, MAC busy time,
total lost packets, and the received beacon messages in both scenarios.
CONTROLLING ADAPTIVE CONTENTION WINDOW TO IMPROVE SAFE MESSAGE RECEIVED RATE ...IJCNCJournal
The primary goal of Vehicular Ad Hoc Networks (VANETs) is to support the secure transmission of applications via vehicles. Broadcasting is an important form of communication in the VANET network. Since there is no recovery for broadcast frames in the VANET network, the rate of receiving safe messages can become very low, especially in dense network conditions. In this paper, we present a new broadcast coordination mechanism with the aim of adaptive control of CW size to improve the received rate of safety messages. Each vehicle in the VANET can identify current local conditions of the network such as collisions or congestion by analyzing recently successfully sent and received frames. Based on the analysis of the received frame rate at each vehicle, the proposed mechanism controls the CW size and uses the EDCA mechanism to prioritize the important data flows. Using a combination of simulation tools in VANET, we build simulation scenarios in different network conditions to evaluate the received rate of safety messages compared to the default mechanism in the 802.11p standard. Simulation results have demonstrated that the proposed mechanism improves the received rate of safety messages better than the default mechanism in the 802.11p standard in all cases.
Controlling Adaptive Contention Window to Improve Safe Message Received Rate ...IJCNCJournal
The primary goal of Vehicular Ad Hoc Networks (VANETs) is to support the secure transmission of applications via vehicles. Broadcasting is an important form of communication in the VANET network. Since there is no recovery for broadcast frames in the VANET network, the rate of receiving safe messages can become very low, especially in dense network conditions. In this paper, we present a new broadcast coordination mechanism with the aim of adaptive control of CW size to improve the received rate of safety messages. Each vehicle in the VANET can identify current local conditions of the network such as collisions or congestion by analyzing recently successfully sent and received frames. Based on the analysis of the received frame rate at each vehicle, the proposed mechanism controls the CW size and uses the EDCA mechanism to prioritize the important data flows. Using a combination of simulation tools in VANET, we build simulation scenarios in different network conditions to evaluate the received rate of safety messages compared to the default mechanism in the 802.11p standard. Simulation results have demonstrated that the proposed mechanism improves the received rate of safety messages better than the default mechanism in the 802.11p standard in all cases.
Distributed Priority based channel access for VANET (DPBCA)Editor IJMTER
IEEE 802.11p vehicular network supports various applications with different
transmission priorities and QoS requirements. It classifies the access categories into four priority
levels to ensure the successful transmission of higher priority traffic compared to lower priority
traffic in a vehicle. But the external collision between traffic of same priority from different vehicles
is not considered. Based on such consideration, this paper proposes a distributed priority based
channel access scheme. In this proposed work, the priority of each vehicle is calculated based on its
stature on the road and access category. The proposed approach can ensure successful transmission
reducing collision leading to overall throughput improvement.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
General Model for Single and Multiple Channels WLANs with Quality of Service ...ijwmn
In this paper we develop an intergraded model for request mechanism and data transmission in the uplink phase in the presence of channel noise. This model supports quality of service. The wireless channel is prone to many impairments. Thus, certain techniques have to be developed to deliver data to the receiver. We calculated the performance parameters for single and multichannel wireless networks, like the requests throughput, data throughput and the requests acceptance probability and data acceptance probability. The proposed model is general model since it can be applied to different wireless networks such as IEEE802.11a, IEEE802.16e, CDMA operated networks and Hiperlan\2.
Channel Aware Mac Protocol for Maximizing Throughput and FairnessIJORCS
The proper channel utilization and the queue length aware routing protocol is a challenging task in MANET. To overcome this drawback we are extending the previous work by improving the MAC protocol to maximize the Throughput and Fairness. In this work we are estimating the channel condition and Contention for a channel aware packet scheduling and the queue length is also calculated for the routing protocol which is aware of the queue length. The channel is scheduled based on the channel condition and the routing is carried out by considering the queue length. This queue length will provide a measurement of traffic load at the mobile node itself. Depending upon this load the node with the lesser load will be selected for the routing; this will effectively balance the load and improve the throughput of the ad hoc network.
Impact of Randomness on MAC Layer Schedulers over High Speed Wireless Campus ...ijcsse
IEEE802.11e standard provides an EDCA mechanism to ensure the QoS using service differentiation function for IMM traffics through the WCN. In an EDCA mechanism, IMM traffics have been classified into four categories and each category has specific priority. Many EDCA schedulers allow these traffics to access the channel based on assigned priorities. The IMM high priority traffic is high delay sensitive and required high bandwidth to ensure QoS over the networks. Scheduling mechanism is the effective way to satisfy IMM traffic but it cannot give guarantee because of the randomness of some EDCA schedulers or proposed networks. In order to provide the QoS, scheduling mechanism is the challenging issue to transmit IMM traffic through the channel and it is still need to be solved over WCN. This work aims to examine the effect of the randomness on different MAC layer schedulers' performance and evaluates the performance of the proposed schedulers using different performance metrics in WCN.
New adaptation method based on cross layer and TCP over protocols to improve ...IJECEIAES
Due to rapid growth of multimedia traffic used over the mobile ad-hoc networks (MANETs), to keep up with the progress of this constraint MANETs protocols becoming increasingly concerned with the quality of service. In view of the random mobility nodes in MANET, TCP becomes more unreliability in case of higher energy consumption and packet loss. In this paper we proposed a new optimization approach to enhance decision making of TCP based on some changes of IEEE 802.11 MAC uses cross layer approach. The aim is to minimize the impact of retransmissions of packet lost and energy consumption in order to analyse and chose the appropriate routing protocol for TCP that can be enhance QoS MANET. Our simulation results based QoS study using NS3 show that, our proposal achieved better performance of TCP in MANETs significantly, and also improved the throughput, energy consumption and facilitates the traffic transmission over routing protocol.
ON DEMAND CHANNEL ASSIGNMENT METHOD FOR CHANNEL DIVERSITY (ODCAM)ijwmn
The IEEE 802.11s Wireless Mesh Networks (WMN) is a new multi-hop technology increasing the coverage
of IEEE 802.11 Wireless Network and providing Internet access. In order to increase the mesh network
capacity, the WMN has evolved from single-radio single-channel architecture to Multi-Channel Multi-
Radios (MC-MR) architecture. In MC-MR the main challenge of the WMN is the channel assignment. In
this article, we propose a new channel assignment method based on channel diversity. This new method
named ODCAM (On Demand channel Assignment Method for channel diversity ) defines a channel
diversity mechanism used to select a new channel along the path between the source and the destination.
The best path between the source and the destination is provided by the HWMP (Hybrid Wireless Mesh
Protocol) protocol using MWCETT (Modified Weighted Cumulative Expected Transmission Time) an
extension of the WCETT metric. The simulation results show the ODCAM performance compared with an
hybrid approach.
Effect of Interleaved FEC Code on Wavelet Based MC-CDMA System with Alamouti ...IJCSEIT Journal
In this paper, the impact of Forward Error Correction (FEC) code namely Trellis code with interleaver on
the performance of wavelet based MC-CDMA wireless communication system with the implementation of
Alamouti antenna diversity scheme has been investigated in terms of Bit Error Rate (BER) as a function of
Signal-to-Noise Ratio (SNR) per bit. Simulation of the system under proposed study has been done in M-ary
modulation schemes (MPSK, MQAM and DPSK) over AWGN and Rayleigh fading channel incorporating
Walsh Hadamard code as orthogonal spreading code to discriminate the message signal for individual
user. It is observed via computer simulation that the performance of the interleaved coded based proposed
system outperforms than that of the uncoded system in all modulation schemes over Rayleigh fading
channel.
Handover Behaviour of Transparent Relay in WiMAX NetworksIDES Editor
The knowledge on handover behaviour in WiMAX
network is essential for network management and planning
in order to achieve optimum system throughput. In this paper
we have analysed the handover behaviour of transparent relay
in several configurations for the IEEE 802.16j Mobile Multihop
Relay (MMR) WiMAX network. The simulation was
performed using NCTUns tool and adopted the hard handover
mechanism for three different relay network topologies with
varying mobile station speeds. The result shows the handover
for internal network is faster than the external network and
by appropriate relay deployment the system throughput can
be increased up to 14.39%.
ACHIEVING ENHANCED THROUGHPUT IN MOBILE ADHOC NETWORK USING COLLISION AWARE M...ijasuc
Since wireless medium is high demand resource the design of an efficient medium access protocol is
important for Mobile Adhoc Networks. As MAC is the base layer in the protocol stack a performance gain
in this layer will have significant improvement in the overall performance of the network. Since the current
IEEE 802.11 MAC standard is not adaptive to the network scenario its performance is poor in terms of
throughput, fairness and delay. Although several alternatives to the existing standard is proposed many of
them are not satisfactorily address the key issues of keeping the simplicity of the protocol and avoiding the
overhead on the nodes on duty in emergency situations where usually adhoc networks are applied. In this
paper we propose an adaptive, collision aware MAC protocol for wireless adhoc networks, termed the
Collision Based Contention (CBC) protocol, in which depends on the current collision level on the shared
medium contending nodes dynamically decides its Backoff value to avoid a blind random waiting before
access to the medium. The CBC scheme outperforms the BEB scheme employed in the IEEE 802.11 MAC
standard and other competing proposals.
Joint Routing and Congestion Control in Multipath Channel based on Signal to ...IJECEIAES
Routing protocol and congestion control in Transmission Control Protocol (TCP) have important roles in wireless mobile network performance. In wireless communication, the stability of the path and successful data transmission will be influenced by the channel condition. This channel condition constraints come from path loss and the multipath channel fading. With these constraints, the algorithm in the routing protocol and congestion control is confronted with the uncertainty of connection quality and probability of successful packet transmission, respectively. It is important to investigate the reliability and robustness of routing protocol and congestion control algorithms in dealing with such situation. In this paper, we develop a detailed approach and analytical throughput performance with a cross layer scheme (CLS) between routing and congestion control mechanism based on signal to noise ratio (SNR) in Rician and Rayleigh as multipath fading channel. We proposed joint routing and congestion control TCP with a cross layer scheme model based on SNR (RTCP-SNR). We compare the performance of RTCP-SNR with conventional routing-TCP and routing-TCP that used CLS with routing aware (RTCP-RA) model. The analyses and the simulation results showed that RTCP-SNR in a multipath channel outperforms conventional routing-TCP and RTCP-RA.
F-802.11P: A Fuzzy Enhancement for IEEE 802.11P in Vehicle-to-Everything Comm...IJCNCJournal
Vehicle-to-Everything communications (V2X) are becoming increasingly popular as a solution for safer roads and better traffic management. One of the essential protocols in V2X is the Dedicated Short Range Communication (DSRC) protocol suite. DSRC includes the IEEE 802.11p protocol that operates at the medium access control (MAC) and physical (PHY) layers. Upon collision, the IEEE 802.11p MAC layer applies a carrier sense multiple access/collision avoidance (CSMA/CA) mechanism that randomly selects a backoff time to re-check the channel activity and then retransmit. However, the random selection of the backoff time may lead to further packet collisions that decrease the utilization of the communication channel, which suffers from a limited bandwidth in the first place. This paper proposes a fuzzy model based on rational decision-making, which we call F-802.11p, to improve the IEEE 802.11p protocol backoff time selection by limiting the IEEE 802.11p beacon messages to better use of the available bandwidth. A simulation study presents the evaluation of our work compared to IEEE 802.11p. We deployed the simulation software in two scenarios: the Veins Framework map and the map of New Administrative Cairo in Egypt. We base our comparison on slots backoff, times into backoff, PHY busy time, MAC busy time, total lost packets, and generated/received beacon messages. Simulation results show that both protocols have comparable results in slots backoff, times into back off, and the generated beacon messages. At the same time, our F-802.11p significantly outperforms the IEEE 802.11p in PHY busy time, MAC busy time, total lost packets, and the received beacon messages in both scenarios.
F-802.11P: A FUZZY ENHANCEMENT FOR IEEE 802.11P IN VEHICLE-TO-EVERYTHING COMM...IJCNCJournal
Vehicle-to-Everything communications (V2X) are becoming increasingly popular as a solution for safer
roads and better traffic management. One of the essential protocols in V2X is the Dedicated Short Range
Communication (DSRC) protocol suite. DSRC includes the IEEE 802.11p protocol that operates at the
medium access control (MAC) and physical (PHY) layers. Upon collision, the IEEE 802.11p MAC layer
applies a carrier sense multiple access/collision avoidance (CSMA/CA) mechanism that randomly selects a
backoff time to re-check the channel activity and then retransmit. However, the random selection of the
backoff time may lead to further packet collisions that decrease the utilization of the communication
channel, which suffers from a limited bandwidth in the first place. This paper proposes a fuzzy model based
on rational decision-making, which we call F-802.11p, to improve the IEEE 802.11p protocol backoff time
selection by limiting the IEEE 802.11p beacon messages to better use of the available bandwidth. A
simulation study presents the evaluation of our work compared to IEEE 802.11p. We deployed the
simulation software in two scenarios: the Veins Framework map and the map of New Administrative Cairo
in Egypt. We base our comparison on slots backoff, times into backoff, PHY busy time, MAC busy time,
total lost packets, and generated/received beacon messages. Simulation results show that both protocols
have comparable results in slots backoff, times into back off, and the generated beacon messages. At the
same time, our F-802.11p significantly outperforms the IEEE 802.11p in PHY busy time, MAC busy time,
total lost packets, and the received beacon messages in both scenarios.
CONTROLLING ADAPTIVE CONTENTION WINDOW TO IMPROVE SAFE MESSAGE RECEIVED RATE ...IJCNCJournal
The primary goal of Vehicular Ad Hoc Networks (VANETs) is to support the secure transmission of applications via vehicles. Broadcasting is an important form of communication in the VANET network. Since there is no recovery for broadcast frames in the VANET network, the rate of receiving safe messages can become very low, especially in dense network conditions. In this paper, we present a new broadcast coordination mechanism with the aim of adaptive control of CW size to improve the received rate of safety messages. Each vehicle in the VANET can identify current local conditions of the network such as collisions or congestion by analyzing recently successfully sent and received frames. Based on the analysis of the received frame rate at each vehicle, the proposed mechanism controls the CW size and uses the EDCA mechanism to prioritize the important data flows. Using a combination of simulation tools in VANET, we build simulation scenarios in different network conditions to evaluate the received rate of safety messages compared to the default mechanism in the 802.11p standard. Simulation results have demonstrated that the proposed mechanism improves the received rate of safety messages better than the default mechanism in the 802.11p standard in all cases.
Controlling Adaptive Contention Window to Improve Safe Message Received Rate ...IJCNCJournal
The primary goal of Vehicular Ad Hoc Networks (VANETs) is to support the secure transmission of applications via vehicles. Broadcasting is an important form of communication in the VANET network. Since there is no recovery for broadcast frames in the VANET network, the rate of receiving safe messages can become very low, especially in dense network conditions. In this paper, we present a new broadcast coordination mechanism with the aim of adaptive control of CW size to improve the received rate of safety messages. Each vehicle in the VANET can identify current local conditions of the network such as collisions or congestion by analyzing recently successfully sent and received frames. Based on the analysis of the received frame rate at each vehicle, the proposed mechanism controls the CW size and uses the EDCA mechanism to prioritize the important data flows. Using a combination of simulation tools in VANET, we build simulation scenarios in different network conditions to evaluate the received rate of safety messages compared to the default mechanism in the 802.11p standard. Simulation results have demonstrated that the proposed mechanism improves the received rate of safety messages better than the default mechanism in the 802.11p standard in all cases.
Distributed Priority based channel access for VANET (DPBCA)Editor IJMTER
IEEE 802.11p vehicular network supports various applications with different
transmission priorities and QoS requirements. It classifies the access categories into four priority
levels to ensure the successful transmission of higher priority traffic compared to lower priority
traffic in a vehicle. But the external collision between traffic of same priority from different vehicles
is not considered. Based on such consideration, this paper proposes a distributed priority based
channel access scheme. In this proposed work, the priority of each vehicle is calculated based on its
stature on the road and access category. The proposed approach can ensure successful transmission
reducing collision leading to overall throughput improvement.
Quality of Service for Video Streaming using EDCA in MANETijsrd.com
Mobile Ad-hoc network(MANET) is a collection of wireless terminals that are able to dynamically form a temporary network. To establish such a network no fixed infrastructure is required. Here, it is the responsibility of network nodes to forward each other's packets and thus these nodes also act as routers. In such a network resources are limited and also topology changes dynamically. So providing Quality of service(QoS) is also necessary. QoS is more important for real time applications for example Video Streaming. IEEE 802.11e network standard supports QoS through EDCA technique. This technique does not fulfill the requirements of QoS. So, in this project modified EDCA technique is proposed to enhance QoS for Video Streaming application. This technique is implemented in NS2 and compared with traditional EDCA.
General Model for Single and Multiple Channels WLANs with Quality of Service...ijwmn
In this paper we develop an intergraded model for request mechanism and data transmission in the uplink
phase in the presence of channel noise. This model supports quality of service. The wireless channel is prone
to many impairments. Thus, certain techniques have to be developed to deliver data to the receiver. We
calculated the performance parameters for single and multichannel wireless networks, like the requests
throughput, data throughput and the requests acceptance probability and data acceptance probability. The
proposed model is general model since it can be applied to different wireless networks such as IEEE802.11a,
IEEE802.16e, CDMA operated networks and Hiperlan\2.
Smart optimization in 802.11p media access control protocol for vehicular ad ...IJECEIAES
The innovative idea presented in this research is that advancements in automotive networks and embedded devices can be used to assess the impact of congestion control on throughput and packet delivery ratio (PDR), or socalled multimedia content delivery. Vehicle networking and the distribution of multimedia content have become essential factors in getting packets to their intended recipients due to the availability of bandwidth. Vehicle-toinfrastructure (V2I) communication systems are crucial in vehicular ad hoc networks (VANETs), which permit vehicles to connect by distributing and delivering traffic data and transmission packet schemes. High levels of mobility and changing network topology necessitate dispersed monitoring and execution for congestion control. The amount of traffic congestion for packet transfers could be reduced by enhancing congestion management in terms of throughput and PDR percentages. In a highway setting, the Taguchi approach has been used to optimize the parameters for congestion control. Based on throughput and PDR performance measures, this technique minimizes superfluous traffic information and lowers the likelihood of network congestion. The simulation results have shown that the proposed approach performs better since it increases network performance while effectively utilizing bandwidth. The effectiveness of the suggested technique is evaluated using a typical VANETs scenario for V2I communication while driving on a highway.
MACHINE LEARNING BASED FRAME SIZE OPTIMIZATION IN WLAN DOWNLINK MU-MIMO CHANN...IJCNCJournal
The key enhancement in the medium access control (MAC) layer is frame aggregation introduced by the
IEEE 802.11n/ac standard to accommodate the growing traffic demand in the WLAN by allowing multiple
packets aggregated per transmission. Frame aggregation efficiently reduces control overhead in the MAC
layer, such as the MAC header and thus it helps to enhance transmission efficiency and throughput
performance of WLAN. However, heterogeneous traffic demand among streams in the WLAN downlink
MU-MIMO channel creates a challenge to efficiently utilize the benefits of frame aggregation.
Transmission efficiency is also compromised during frame size setting determination because when a
frame size is larger, the impact of the overhead frame can be lower, but they are also more vulnerable to
transmission errors. Thus, this trade-off between maximizing frame size and minimizing overhead frames
should be addressed by employing an adaptive frame aggregation technique to derive the optimal frame
size that would maximize the throughput in WLAN downlink MU-MIMO channel. Moreover, when frame
aggregation approach is employed, more frames must wait before transmission in a buffer which causes a
delay in the performance of WLAN. Thus, analysing the trade-off between maximizing throughput and
minimizing delay is a critical issue that should also be addressed to enhance the performance of WLAN.
However, the majority of the existing adaptive aggregation algorithms in the WLAN downlink MU-MIMO
channel are focused to maximize the throughput or minimize the delay. The main contribution of this paper
is to propose a machine learning-based frame size optimization algorithm by extending our earlier
approach in considering the cost of delay to maximize the system throughput of WLAN. The effectiveness of
the proposed scheme is evaluated over the FIFO Baseline Approach and earlier conventional approaches
under the effects of various traffic patterns, channel conditions, and the number of STAs.
Machine Learning based Frame Size Optimization in WLAN Downlink MU-MIMO Chann...IJCNCJournal
The key enhancement in the medium access control (MAC) layer is frame aggregation introduced by the IEEE 802.11n/ac standard to accommodate the growing traffic demand in the WLAN by allowing multiple packets aggregated per transmission. Frame aggregation efficiently reduces control overhead in the MAC layer, such as the MAC header and thus it helps to enhance transmission efficiency and throughput performance of WLAN. However, heterogeneous traffic demand among streams in the WLAN downlink MU-MIMO channel creates a challenge to efficiently utilize the benefits of frame aggregation. Transmission efficiency is also compromised during frame size setting determination because when a frame size is larger, the impact of the overhead frame can be lower, but they are also more vulnerable to transmission errors. Thus, this trade-off between maximizing frame size and minimizing overhead frames should be addressed by employing an adaptive frame aggregation technique to derive the optimal frame size that would maximize the throughput in WLAN downlink MU-MIMO channel. Moreover, when frame aggregation approach is employed, more frames must wait before transmission in a buffer which causes a delay in the performance of WLAN. Thus, analysing the trade-off between maximizing throughput and minimizing delay is a critical issue that should also be addressed to enhance the performance of WLAN. However, the majority of the existing adaptive aggregation algorithms in the WLAN downlink MU-MIMO channel are focused to maximize the throughput or minimize the delay. The main contribution of this paper is to propose a machine learning-based frame size optimization algorithm by extending our earlier approach in considering the cost of delay to maximize the system throughput of WLAN. The effectiveness of the proposed scheme is evaluated over the FIFO Baseline Approach and earlier conventional approaches under the effects of various traffic patterns, channel conditions, and the number of STAs.
Quality of service adaptive modulation and coding scheme for IEEE 802.11acIJECEIAES
Nowadays, the rising demand for digital communication technologies has contributed to the increase in the volume of traffic. This continuous trend of internet traffic has led to the deterioration of the quality of service (QoS) with reduced throughput and increased latency. This also is due to the proliferation of new broadband applications which require low latency and high throughput such as virtual reality and real-time gaming. Therefore, considering the aforementioned challenge in QoS of wireless networks, a link adaptation method is suggested in this study, in order to enhance the performance of the QoS in IEEE 802.11ac amendment wireless local-area network (WLAN). The proposed technique adaptively changes the transmission data rate by increasing or decreasing the modulation and coding scheme (MCS) level according to the traffic conditions. With the use of an OMNeT++ computer-aided design (CAD)-based simulation model, the effectiveness of the suggested approach is examined. Simulated findings were compared with the link adaptation approach of the default condition. The results of the simulation demonstrate that the proposed technique significantly increases throughput (36.48%) and decreases latency in comparison to the default situation. These findings demonstrate the technique's potential to improve WLAN QoS efficiency, notably in regard to throughput and latency.
CROSS LAYER DESIGN APPROACH FOR EFFICIENT DATA DELIVERY BASED ON IEEE 802.11P...pijans
Intelligent Transportation Systems (ITS) have been one of the promising technology that has a great interest attention from many researchers over the world. Vehicular Ad-hoc Network (VANET) communications environment as a part of ITS opens the way for a wide range of applications such as safety applications, mobility and connectivity for both driver and passengers to exploit the transport systems in a smoothly, efficiently and safer way. Several challenging tasks facing adopting VANET functionality for ITS such as modelling of wireless transmission and routing issues. These research issues have become more critical due to the high mobility of vehicles nodes (transmitters and receivers) and unexpected network topology due to the high speed of nodes. In fact, modelling radio propagation channel in VANET environment which considers as one of a stringent communications environment is a challenging task. The selection of a suitable transmission model plays a key role in the routing decisions for VANET. Different propagation models allow calculating the Received Signal Strength (RSS) based on key environmental properties such as the distance between transmitter vehicle and a receiver vehicle, the gain and antenna height of transmitter and a receiver vehicles. Hence, it is useful to calculate RSS and SNR values for a specific propagation model and then these values can be used later for routing decision in order to find the best path with high SNR. This paper evaluates the performance of different transmission models (freespace, two-ray and log-normal) in terms of Receive Signal Strength (RSS). In addition, the performance of such wireless transmission models for vehicular communication in terms of PDR, throughput and delay is evaluated by applying the proposed cross layer routing approach based on IEEE 802.11p. By using MATLAB, the obtained results confirm the best packet delivery ratio for our proposed approach, where it indicates poor quality of DSSS PHY with high number vehicles. The minimum delay achieved when traffic density is decreased.
CROSS LAYER DESIGN APPROACH FOR EFFICIENT DATA DELIVERY BASED ON IEEE 802.11P...pijans
Intelligent Transportation Systems (ITS) have been one of the promising technology that has a great
interest attention from many researchers over the world. Vehicular Ad-hoc Network (VANET)
communications environment as a part of ITS opens the way for a wide range of applications such as safety
applications, mobility and connectivity for both driver and passengers to exploit the transport systems in a
smoothly, efficiently and safer way. Several challenging tasks facing adopting VANET functionality for ITS
such as modelling of wireless transmission and routing issues. These research issues have become more
critical due to the high mobility of vehicles nodes (transmitters and receivers) and unexpected network
topology due to the high speed of nodes. In fact, modelling radio propagation channel in VANET
environment which considers as one of a stringent communications environment is a challenging task. The
selection of a suitable transmission model plays a key role in the routing decisions for VANET. Different
propagation models allow calculating the Received Signal Strength (RSS) based on key environmental
properties such as the distance between transmitter vehicle and a receiver vehicle, the gain and antenna
height of transmitter and a receiver vehicles. Hence, it is useful to calculate RSS and SNR values for a
specific propagation model and then these values can be used later for routing decision in order to find the
best path with high SNR. This paper evaluates the performance of different transmission models (free-
space, two-ray and log-normal) in terms of Receive Signal Strength (RSS). In addition, the performance of
such wireless transmission models for vehicular communication in terms of PDR, throughput and delay is
evaluated by applying the proposed cross layer routing approach based on IEEE 802.11p. By using
MATLAB, the obtained results confirm the best packet delivery ratio for our proposed approach, where it
indicates poor quality of DSSS PHY with high number vehicles. The minimum delay achieved when traffic
density is decreased
An effective transmit packet coding with trust-based relay nodes in VANETsjournalBEEI
Vehicular ad-hoc networks (VANETs) are characterized by limited network resources such as limited bandwidth and battery capacity. Hence, it is necessary that unnecessary use of network resources (such as unnecessary packet transfers) is reduced in such networks so that the available power can be conserved for efficient multicast communications. In this paper, we have presented a Transmit Packet Coding (TPC) Network Coding in VANET to ensure reliable and efficient multicasting. With network coding, the number of transmitted packets over the network can be reduced, ensuring efficient utilization of network devices and resources. Here, the trust-based graph optimization is performed using Cuckoo search algorithm to select the secure relay nodes. The experimental results showed the superiority of the presented approach compared to the existing techniques in terms of throughput, latency, hop delay, packet delivery ratio, network decoder outage probability, and block error rate.
Bibliometric analysis highlighting the role of women in addressing climate ch...IJECEIAES
Fossil fuel consumption increased quickly, contributing to climate change
that is evident in unusual flooding and draughts, and global warming. Over
the past ten years, women's involvement in society has grown dramatically,
and they succeeded in playing a noticeable role in reducing climate change.
A bibliometric analysis of data from the last ten years has been carried out to
examine the role of women in addressing the climate change. The analysis's
findings discussed the relevant to the sustainable development goals (SDGs),
particularly SDG 7 and SDG 13. The results considered contributions made
by women in the various sectors while taking geographic dispersion into
account. The bibliometric analysis delves into topics including women's
leadership in environmental groups, their involvement in policymaking, their
contributions to sustainable development projects, and the influence of
gender diversity on attempts to mitigate climate change. This study's results
highlight how women have influenced policies and actions related to climate
change, point out areas of research deficiency and recommendations on how
to increase role of the women in addressing the climate change and
achieving sustainability. To achieve more successful results, this initiative
aims to highlight the significance of gender equality and encourage
inclusivity in climate change decision-making processes.
Voltage and frequency control of microgrid in presence of micro-turbine inter...IJECEIAES
The active and reactive load changes have a significant impact on voltage
and frequency. In this paper, in order to stabilize the microgrid (MG) against
load variations in islanding mode, the active and reactive power of all
distributed generators (DGs), including energy storage (battery), diesel
generator, and micro-turbine, are controlled. The micro-turbine generator is
connected to MG through a three-phase to three-phase matrix converter, and
the droop control method is applied for controlling the voltage and
frequency of MG. In addition, a method is introduced for voltage and
frequency control of micro-turbines in the transition state from gridconnected mode to islanding mode. A novel switching strategy of the matrix
converter is used for converting the high-frequency output voltage of the
micro-turbine to the grid-side frequency of the utility system. Moreover,
using the switching strategy, the low-order harmonics in the output current
and voltage are not produced, and consequently, the size of the output filter
would be reduced. In fact, the suggested control strategy is load-independent
and has no frequency conversion restrictions. The proposed approach for
voltage and frequency regulation demonstrates exceptional performance and
favorable response across various load alteration scenarios. The suggested
strategy is examined in several scenarios in the MG test systems, and the
simulation results are addressed.
Enhancing battery system identification: nonlinear autoregressive modeling fo...IJECEIAES
Precisely characterizing Li-ion batteries is essential for optimizing their
performance, enhancing safety, and prolonging their lifespan across various
applications, such as electric vehicles and renewable energy systems. This
article introduces an innovative nonlinear methodology for system
identification of a Li-ion battery, employing a nonlinear autoregressive with
exogenous inputs (NARX) model. The proposed approach integrates the
benefits of nonlinear modeling with the adaptability of the NARX structure,
facilitating a more comprehensive representation of the intricate
electrochemical processes within the battery. Experimental data collected
from a Li-ion battery operating under diverse scenarios are employed to
validate the effectiveness of the proposed methodology. The identified
NARX model exhibits superior accuracy in predicting the battery's behavior
compared to traditional linear models. This study underscores the
importance of accounting for nonlinearities in battery modeling, providing
insights into the intricate relationships between state-of-charge, voltage, and
current under dynamic conditions.
Smart grid deployment: from a bibliometric analysis to a surveyIJECEIAES
Smart grids are one of the last decades' innovations in electrical energy.
They bring relevant advantages compared to the traditional grid and
significant interest from the research community. Assessing the field's
evolution is essential to propose guidelines for facing new and future smart
grid challenges. In addition, knowing the main technologies involved in the
deployment of smart grids (SGs) is important to highlight possible
shortcomings that can be mitigated by developing new tools. This paper
contributes to the research trends mentioned above by focusing on two
objectives. First, a bibliometric analysis is presented to give an overview of
the current research level about smart grid deployment. Second, a survey of
the main technological approaches used for smart grid implementation and
their contributions are highlighted. To that effect, we searched the Web of
Science (WoS), and the Scopus databases. We obtained 5,663 documents
from WoS and 7,215 from Scopus on smart grid implementation or
deployment. With the extraction limitation in the Scopus database, 5,872 of
the 7,215 documents were extracted using a multi-step process. These two
datasets have been analyzed using a bibliometric tool called bibliometrix.
The main outputs are presented with some recommendations for future
research.
Use of analytical hierarchy process for selecting and prioritizing islanding ...IJECEIAES
One of the problems that are associated to power systems is islanding
condition, which must be rapidly and properly detected to prevent any
negative consequences on the system's protection, stability, and security.
This paper offers a thorough overview of several islanding detection
strategies, which are divided into two categories: classic approaches,
including local and remote approaches, and modern techniques, including
techniques based on signal processing and computational intelligence.
Additionally, each approach is compared and assessed based on several
factors, including implementation costs, non-detected zones, declining
power quality, and response times using the analytical hierarchy process
(AHP). The multi-criteria decision-making analysis shows that the overall
weight of passive methods (24.7%), active methods (7.8%), hybrid methods
(5.6%), remote methods (14.5%), signal processing-based methods (26.6%),
and computational intelligent-based methods (20.8%) based on the
comparison of all criteria together. Thus, it can be seen from the total weight
that hybrid approaches are the least suitable to be chosen, while signal
processing-based methods are the most appropriate islanding detection
method to be selected and implemented in power system with respect to the
aforementioned factors. Using Expert Choice software, the proposed
hierarchy model is studied and examined.
Enhancing of single-stage grid-connected photovoltaic system using fuzzy logi...IJECEIAES
The power generated by photovoltaic (PV) systems is influenced by
environmental factors. This variability hampers the control and utilization of
solar cells' peak output. In this study, a single-stage grid-connected PV
system is designed to enhance power quality. Our approach employs fuzzy
logic in the direct power control (DPC) of a three-phase voltage source
inverter (VSI), enabling seamless integration of the PV connected to the
grid. Additionally, a fuzzy logic-based maximum power point tracking
(MPPT) controller is adopted, which outperforms traditional methods like
incremental conductance (INC) in enhancing solar cell efficiency and
minimizing the response time. Moreover, the inverter's real-time active and
reactive power is directly managed to achieve a unity power factor (UPF).
The system's performance is assessed through MATLAB/Simulink
implementation, showing marked improvement over conventional methods,
particularly in steady-state and varying weather conditions. For solar
irradiances of 500 and 1,000 W/m2
, the results show that the proposed
method reduces the total harmonic distortion (THD) of the injected current
to the grid by approximately 46% and 38% compared to conventional
methods, respectively. Furthermore, we compare the simulation results with
IEEE standards to evaluate the system's grid compatibility.
Enhancing photovoltaic system maximum power point tracking with fuzzy logic-b...IJECEIAES
Photovoltaic systems have emerged as a promising energy resource that
caters to the future needs of society, owing to their renewable, inexhaustible,
and cost-free nature. The power output of these systems relies on solar cell
radiation and temperature. In order to mitigate the dependence on
atmospheric conditions and enhance power tracking, a conventional
approach has been improved by integrating various methods. To optimize
the generation of electricity from solar systems, the maximum power point
tracking (MPPT) technique is employed. To overcome limitations such as
steady-state voltage oscillations and improve transient response, two
traditional MPPT methods, namely fuzzy logic controller (FLC) and perturb
and observe (P&O), have been modified. This research paper aims to
simulate and validate the step size of the proposed modified P&O and FLC
techniques within the MPPT algorithm using MATLAB/Simulink for
efficient power tracking in photovoltaic systems.
Adaptive synchronous sliding control for a robot manipulator based on neural ...IJECEIAES
Robot manipulators have become important equipment in production lines, medical fields, and transportation. Improving the quality of trajectory tracking for
robot hands is always an attractive topic in the research community. This is a
challenging problem because robot manipulators are complex nonlinear systems
and are often subject to fluctuations in loads and external disturbances. This
article proposes an adaptive synchronous sliding control scheme to improve trajectory tracking performance for a robot manipulator. The proposed controller
ensures that the positions of the joints track the desired trajectory, synchronize
the errors, and significantly reduces chattering. First, the synchronous tracking
errors and synchronous sliding surfaces are presented. Second, the synchronous
tracking error dynamics are determined. Third, a robust adaptive control law is
designed,the unknown components of the model are estimated online by the neural network, and the parameters of the switching elements are selected by fuzzy
logic. The built algorithm ensures that the tracking and approximation errors
are ultimately uniformly bounded (UUB). Finally, the effectiveness of the constructed algorithm is demonstrated through simulation and experimental results.
Simulation and experimental results show that the proposed controller is effective with small synchronous tracking errors, and the chattering phenomenon is
significantly reduced.
Remote field-programmable gate array laboratory for signal acquisition and de...IJECEIAES
A remote laboratory utilizing field-programmable gate array (FPGA) technologies enhances students’ learning experience anywhere and anytime in embedded system design. Existing remote laboratories prioritize hardware access and visual feedback for observing board behavior after programming, neglecting comprehensive debugging tools to resolve errors that require internal signal acquisition. This paper proposes a novel remote embeddedsystem design approach targeting FPGA technologies that are fully interactive via a web-based platform. Our solution provides FPGA board access and debugging capabilities beyond the visual feedback provided by existing remote laboratories. We implemented a lab module that allows users to seamlessly incorporate into their FPGA design. The module minimizes hardware resource utilization while enabling the acquisition of a large number of data samples from the signal during the experiments by adaptively compressing the signal prior to data transmission. The results demonstrate an average compression ratio of 2.90 across three benchmark signals, indicating efficient signal acquisition and effective debugging and analysis. This method allows users to acquire more data samples than conventional methods. The proposed lab allows students to remotely test and debug their designs, bridging the gap between theory and practice in embedded system design.
Detecting and resolving feature envy through automated machine learning and m...IJECEIAES
Efficiently identifying and resolving code smells enhances software project quality. This paper presents a novel solution, utilizing automated machine learning (AutoML) techniques, to detect code smells and apply move method refactoring. By evaluating code metrics before and after refactoring, we assessed its impact on coupling, complexity, and cohesion. Key contributions of this research include a unique dataset for code smell classification and the development of models using AutoGluon for optimal performance. Furthermore, the study identifies the top 20 influential features in classifying feature envy, a well-known code smell, stemming from excessive reliance on external classes. We also explored how move method refactoring addresses feature envy, revealing reduced coupling and complexity, and improved cohesion, ultimately enhancing code quality. In summary, this research offers an empirical, data-driven approach, integrating AutoML and move method refactoring to optimize software project quality. Insights gained shed light on the benefits of refactoring on code quality and the significance of specific features in detecting feature envy. Future research can expand to explore additional refactoring techniques and a broader range of code metrics, advancing software engineering practices and standards.
Smart monitoring technique for solar cell systems using internet of things ba...IJECEIAES
Rapidly and remotely monitoring and receiving the solar cell systems status parameters, solar irradiance, temperature, and humidity, are critical issues in enhancement their efficiency. Hence, in the present article an improved smart prototype of internet of things (IoT) technique based on embedded system through NodeMCU ESP8266 (ESP-12E) was carried out experimentally. Three different regions at Egypt; Luxor, Cairo, and El-Beheira cities were chosen to study their solar irradiance profile, temperature, and humidity by the proposed IoT system. The monitoring data of solar irradiance, temperature, and humidity were live visualized directly by Ubidots through hypertext transfer protocol (HTTP) protocol. The measured solar power radiation in Luxor, Cairo, and El-Beheira ranged between 216-1000, 245-958, and 187-692 W/m 2 respectively during the solar day. The accuracy and rapidity of obtaining monitoring results using the proposed IoT system made it a strong candidate for application in monitoring solar cell systems. On the other hand, the obtained solar power radiation results of the three considered regions strongly candidate Luxor and Cairo as suitable places to build up a solar cells system station rather than El-Beheira.
An efficient security framework for intrusion detection and prevention in int...IJECEIAES
Over the past few years, the internet of things (IoT) has advanced to connect billions of smart devices to improve quality of life. However, anomalies or malicious intrusions pose several security loopholes, leading to performance degradation and threat to data security in IoT operations. Thereby, IoT security systems must keep an eye on and restrict unwanted events from occurring in the IoT network. Recently, various technical solutions based on machine learning (ML) models have been derived towards identifying and restricting unwanted events in IoT. However, most ML-based approaches are prone to miss-classification due to inappropriate feature selection. Additionally, most ML approaches applied to intrusion detection and prevention consider supervised learning, which requires a large amount of labeled data to be trained. Consequently, such complex datasets are impossible to source in a large network like IoT. To address this problem, this proposed study introduces an efficient learning mechanism to strengthen the IoT security aspects. The proposed algorithm incorporates supervised and unsupervised approaches to improve the learning models for intrusion detection and mitigation. Compared with the related works, the experimental outcome shows that the model performs well in a benchmark dataset. It accomplishes an improved detection accuracy of approximately 99.21%.
Developing a smart system for infant incubators using the internet of things ...IJECEIAES
This research is developing an incubator system that integrates the internet of things and artificial intelligence to improve care for premature babies. The system workflow starts with sensors that collect data from the incubator. Then, the data is sent in real-time to the internet of things (IoT) broker eclipse mosquito using the message queue telemetry transport (MQTT) protocol version 5.0. After that, the data is stored in a database for analysis using the long short-term memory network (LSTM) method and displayed in a web application using an application programming interface (API) service. Furthermore, the experimental results produce as many as 2,880 rows of data stored in the database. The correlation coefficient between the target attribute and other attributes ranges from 0.23 to 0.48. Next, several experiments were conducted to evaluate the model-predicted value on the test data. The best results are obtained using a two-layer LSTM configuration model, each with 60 neurons and a lookback setting 6. This model produces an R 2 value of 0.934, with a root mean square error (RMSE) value of 0.015 and a mean absolute error (MAE) of 0.008. In addition, the R 2 value was also evaluated for each attribute used as input, with a result of values between 0.590 and 0.845.
A review on internet of things-based stingless bee's honey production with im...IJECEIAES
Honey is produced exclusively by honeybees and stingless bees which both are well adapted to tropical and subtropical regions such as Malaysia. Stingless bees are known for producing small amounts of honey and are known for having a unique flavor profile. Problem identified that many stingless bees collapsed due to weather, temperature and environment. It is critical to understand the relationship between the production of stingless bee honey and environmental conditions to improve honey production. Thus, this paper presents a review on stingless bee's honey production and prediction modeling. About 54 previous research has been analyzed and compared in identifying the research gaps. A framework on modeling the prediction of stingless bee honey is derived. The result presents the comparison and analysis on the internet of things (IoT) monitoring systems, honey production estimation, convolution neural networks (CNNs), and automatic identification methods on bee species. It is identified based on image detection method the top best three efficiency presents CNN is at 98.67%, densely connected convolutional networks with YOLO v3 is 97.7%, and DenseNet201 convolutional networks 99.81%. This study is significant to assist the researcher in developing a model for predicting stingless honey produced by bee's output, which is important for a stable economy and food security.
A trust based secure access control using authentication mechanism for intero...IJECEIAES
The internet of things (IoT) is a revolutionary innovation in many aspects of our society including interactions, financial activity, and global security such as the military and battlefield internet. Due to the limited energy and processing capacity of network devices, security, energy consumption, compatibility, and device heterogeneity are the long-term IoT problems. As a result, energy and security are critical for data transmission across edge and IoT networks. Existing IoT interoperability techniques need more computation time, have unreliable authentication mechanisms that break easily, lose data easily, and have low confidentiality. In this paper, a key agreement protocol-based authentication mechanism for IoT devices is offered as a solution to this issue. This system makes use of information exchange, which must be secured to prevent access by unauthorized users. Using a compact contiki/cooja simulator, the performance and design of the suggested framework are validated. The simulation findings are evaluated based on detection of malicious nodes after 60 minutes of simulation. The suggested trust method, which is based on privacy access control, reduced packet loss ratio to 0.32%, consumed 0.39% power, and had the greatest average residual energy of 0.99 mJoules at 10 nodes.
Fuzzy linear programming with the intuitionistic polygonal fuzzy numbersIJECEIAES
In real world applications, data are subject to ambiguity due to several factors; fuzzy sets and fuzzy numbers propose a great tool to model such ambiguity. In case of hesitation, the complement of a membership value in fuzzy numbers can be different from the non-membership value, in which case we can model using intuitionistic fuzzy numbers as they provide flexibility by defining both a membership and a non-membership functions. In this article, we consider the intuitionistic fuzzy linear programming problem with intuitionistic polygonal fuzzy numbers, which is a generalization of the previous polygonal fuzzy numbers found in the literature. We present a modification of the simplex method that can be used to solve any general intuitionistic fuzzy linear programming problem after approximating the problem by an intuitionistic polygonal fuzzy number with n edges. This method is given in a simple tableau formulation, and then applied on numerical examples for clarity.
The performance of artificial intelligence in prostate magnetic resonance im...IJECEIAES
Prostate cancer is the predominant form of cancer observed in men worldwide. The application of magnetic resonance imaging (MRI) as a guidance tool for conducting biopsies has been established as a reliable and well-established approach in the diagnosis of prostate cancer. The diagnostic performance of MRI-guided prostate cancer diagnosis exhibits significant heterogeneity due to the intricate and multi-step nature of the diagnostic pathway. The development of artificial intelligence (AI) models, specifically through the utilization of machine learning techniques such as deep learning, is assuming an increasingly significant role in the field of radiology. In the realm of prostate MRI, a considerable body of literature has been dedicated to the development of various AI algorithms. These algorithms have been specifically designed for tasks such as prostate segmentation, lesion identification, and classification. The overarching objective of these endeavors is to enhance diagnostic performance and foster greater agreement among different observers within MRI scans for the prostate. This review article aims to provide a concise overview of the application of AI in the field of radiology, with a specific focus on its utilization in prostate MRI.
Seizure stage detection of epileptic seizure using convolutional neural networksIJECEIAES
According to the World Health Organization (WHO), seventy million individuals worldwide suffer from epilepsy, a neurological disorder. While electroencephalography (EEG) is crucial for diagnosing epilepsy and monitoring the brain activity of epilepsy patients, it requires a specialist to examine all EEG recordings to find epileptic behavior. This procedure needs an experienced doctor, and a precise epilepsy diagnosis is crucial for appropriate treatment. To identify epileptic seizures, this study employed a convolutional neural network (CNN) based on raw scalp EEG signals to discriminate between preictal, ictal, postictal, and interictal segments. The possibility of these characteristics is explored by examining how well timedomain signals work in the detection of epileptic signals using intracranial Freiburg Hospital (FH), scalp Children's Hospital Boston-Massachusetts Institute of Technology (CHB-MIT) databases, and Temple University Hospital (TUH) EEG. To test the viability of this approach, two types of experiments were carried out. Firstly, binary class classification (preictal, ictal, postictal each versus interictal) and four-class classification (interictal versus preictal versus ictal versus postictal). The average accuracy for stage detection using CHB-MIT database was 84.4%, while the Freiburg database's time-domain signals had an accuracy of 79.7% and the highest accuracy of 94.02% for classification in the TUH EEG database when comparing interictal stage to preictal stage.
Analysis of driving style using self-organizing maps to analyze driver behaviorIJECEIAES
Modern life is strongly associated with the use of cars, but the increase in acceleration speeds and their maneuverability leads to a dangerous driving style for some drivers. In these conditions, the development of a method that allows you to track the behavior of the driver is relevant. The article provides an overview of existing methods and models for assessing the functioning of motor vehicles and driver behavior. Based on this, a combined algorithm for recognizing driving style is proposed. To do this, a set of input data was formed, including 20 descriptive features: About the environment, the driver's behavior and the characteristics of the functioning of the car, collected using OBD II. The generated data set is sent to the Kohonen network, where clustering is performed according to driving style and degree of danger. Getting the driving characteristics into a particular cluster allows you to switch to the private indicators of an individual driver and considering individual driving characteristics. The application of the method allows you to identify potentially dangerous driving styles that can prevent accidents.
Hyperspectral object classification using hybrid spectral-spatial fusion and ...IJECEIAES
Because of its spectral-spatial and temporal resolution of greater areas, hyperspectral imaging (HSI) has found widespread application in the field of object classification. The HSI is typically used to accurately determine an object's physical characteristics as well as to locate related objects with appropriate spectral fingerprints. As a result, the HSI has been extensively applied to object identification in several fields, including surveillance, agricultural monitoring, environmental research, and precision agriculture. However, because of their enormous size, objects require a lot of time to classify; for this reason, both spectral and spatial feature fusion have been completed. The existing classification strategy leads to increased misclassification, and the feature fusion method is unable to preserve semantic object inherent features; This study addresses the research difficulties by introducing a hybrid spectral-spatial fusion (HSSF) technique to minimize feature size while maintaining object intrinsic qualities; Lastly, a soft-margins kernel is proposed for multi-layer deep support vector machine (MLDSVM) to reduce misclassification. The standard Indian pines dataset is used for the experiment, and the outcome demonstrates that the HSSF-MLDSVM model performs substantially better in terms of accuracy and Kappa coefficient.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Vaccine management system project report documentation..pdfKamal Acharya
The Division of Vaccine and Immunization is facing increasing difficulty monitoring vaccines and other commodities distribution once they have been distributed from the national stores. With the introduction of new vaccines, more challenges have been anticipated with this additions posing serious threat to the already over strained vaccine supply chain system in Kenya.
Quality defects in TMT Bars, Possible causes and Potential Solutions.PrashantGoswami42
Maintaining high-quality standards in the production of TMT bars is crucial for ensuring structural integrity in construction. Addressing common defects through careful monitoring, standardized processes, and advanced technology can significantly improve the quality of TMT bars. Continuous training and adherence to quality control measures will also play a pivotal role in minimizing these defects.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
AIRCRAFT GENERAL
The Single Aisle is the most advanced family aircraft in service today, with fly-by-wire flight controls.
The A318, A319, A320 and A321 are twin-engine subsonic medium range aircraft.
The family offers a choice of engines
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
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communications, as shown in Figure 1 [2]. The communication in VANETs is either directly if the vehicles
are within the transmission range of each other, or they cooperate in a multi-hop fashion in order to send
packets from the source to destination. Moreover, VANETs applications are separated into two categories
based on prioritization, safety applications with higher priority and service applications with lower priority.
The safety applications include 1) event-driven messages (emergency messages usually related to safety such
as electronic brake warning, post-crash notification and oncoming traffic warning); and 2) periodic messages
which give information on the current status of vehicles to control the traffic (position, speed, and direction).
Meanwhile, the service applications aim to improve driving comfort and the efficiency of transportation such
as parking availability notification, parking payment, electronic toll collect and service announcements.
Therefore, safety applications require assurance in terms of communication reliability and delay. On the other
hand, service applications are more throughput-sensitive instead of delay-sensitive.
Figure 1. VANET Architectures
However, in order to provide different types of application in VANETs, Federal Communications
Commission (FCC) has allocated a frequency band of 5.9 GHz on a total bandwidth of 75 MHz to support 7
channels of 10MHZ for each channel, and 5 MHz for guard band under DSRC protocol, as in Figure 2 [3].
These channels are divided functionally into one control channel (CCH_178), and up to six are service
channels (SCHs). The CCH is used to broadcast safety-critical messages and regular traffic like beacons and
WAVE Service Announcement (WSAs), while the six other channels, SCHs, are dedicated to transmit
service messages. The repeating synchronization intervals (SI) for the channels to transmit the packet is 100
ms, and each SI is divided into CCH Intervals (CCHI) of 50 ms and SCH Intervals (SCHI) of 50 ms. as
illustrated in Figure 3. Based on the IEEE 1609.4 (legacy), during the interval of CCH, the channel activity
on all SCHs is suspended and vice versa. Synchronization between vehicles is achieved by receiving the
coordinated universal time (UTC) provided by the navigation satellite system (GPS) equipped in each
vehicle. In VANETs, the Medium Access Control (MAC) layer of 802.11p uses the enhanced distributed
channel access (EDCA) based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)
mechanism which is derived from IEEE 802.11e to improve the Quality of Service (QoS) [3],[4]. Generally,
prioritization of EDCA scheme is achieved by changing the Contention Windows (CWs) and the Arbitration
Inter-Frame Spaces (AIFS) sizes, which increase the probability of successful medium access for real-time
messages [5].
Figure 2. DSRC Spectrum Band and Channels in The U.S.
(a) Vehicle-to-Vehicle Ad Hoc
Network
(b) Vehicle-to-Infrastructure
Network
(c) Hybrid Architecture
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Figure 3. Synchronization Interval, Guard Interval, CCH Interval, and SCH Interval
This paper aims to provide an extension to the existing model, by adding back-off freezing timer to
the safety and service application models and back-off stages, along with short retry limit to the service
applications models to accommodate the IEEE 802.11p specifications. Therefore, we used 1-D and 2-D
Markov chain models to analyze the safety and non-safety applications respectively, under non-saturated
conditions. We added an idle state to the models to represent the empty buffer when no packet is ready for
transmission. The reason for choosing unsaturated traffic in our models is to simply control the traffic arrival
rate on the network based on the situation; the real network conditions are mostly unsaturated, and saturated
traffic sometimes makes the network unstable [6], [7]. Typically, VANETs support broadcast mode and
acknowledgement (ACK) mechanism for safety and service applications, respectively. The presented work in
this paper took into account the freezing of back-off timer for both safety and service applications models,
and back-off stages along with short retry limit for the service applications model in order to accommodate
the IEEE 802.11p specifications. Hence, taking these elements into consideration are important in modeling
the system to provide an accurate estimation of the channel access, and guarantees that no packet is served
indefinitely. Consequently, it yields more precise results of the system packet delivery ratio.
The rest of the paper is organized as follows. The related works are presented in section 2. In
section 3, we demonstrate the analytical model used in this study that includes probability of frame
transmission using TDMA access method and probability of frame transmission using CSMA/CA
access method. Section 4 elaborates the results and performance analysis of the models. The paper is
concluded in Section 5.
2. RELATED WORK
The principle analysis of IEEE 802.11 Distributed Coordination Function (DCF) was introduced
by [8]. Bianchi proposed bi-directional Markov Chain model to analyze the performance of MAC DCF
mechanism by computing the throughput, assuming saturated traffic and error free channel. The frame retry
limit and back-off freezing has not been considered in [8]. Several works such as [9], [10] followed Bianchi’s
model by analyzing the throughput and delay of IEEE 802.11 DCF under saturated traffic with some
improvements to the principle. In [9], the authors extended Bianchi’s model by taking the frame retry limits
into consideration, the prediction of throughput of 802.11 DCF was more precise in this model. The authors
in [10] analyzed the saturation throughput, taking into account the channel errors and capture effects. Unlike
saturated traffic, the analytical performance of IEEE 802.11 DCF under non-saturated traffic was presented
by [11], [12]. The authors in [11] adjusted the multi-dimensional Markov Chain model by adding one more
state which describes the model when there is no packet available in the buffer to be transmitted, known as
the post-back-off state. The throughput and channel load analysis have been described by [12], taking into
account the short retry limit. However, freezing of the back-off timer was not taken into consideration
in [12]. Likewise, IEEE 802.11e enhanced distributed channel access (EDCA) was analyzed theoretically
under saturation throughput by [13]. The model offered ACK and RTS/CTS mechanisms under a channel
error transmission with priority scheme in order to meet the EDCA specifications. Since the vital
communication in VANETs is a broadcasting mode, [14-17] discussed VANETs’ theoretical performance
which employed high priority-based broadcast for safety applications based on one-dimensional (1-D)
Markov chain model to calculate the throughput and delay for emergency, and routine applications. Unlike
the analysis of IEEE 802.11p for safety applications, the analytical model of VANETs for service
applications was introduced by [18-20] based on bi-dimensional Markov chain model. More analytical study
of throughput was represented by [19], taking into account the EDCA mechanism specification such as
different CWs and AIFS for each ACs and internal collisions. Unlike saturated traffic, [20] analyzed the
performance of IEEE 802.11p based on MAC for both safety and service applications under non-saturated
traffic. The analyses of delay, packet delivery ratio and throughput were included in the model. However, in
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order to improve the reliability of the safety applications among vehicles, the HER-MAC protocol [21]
allows vehicles to broadcast their safety applications in the reserved slot time, utilizing whole the SI
(100 ms); this makes the HER-MAC protocol exploits the channels efficiently. The authors proposed 1-D and
2-D Markov chain models to analyze and evaluate the performance of HER-MAC protocol under non-
saturated conditions in term of packet delivery ratio. However, the frame retry limit for service applications
and the freezing of the back-off timer for both applications were not considered in model, which means that
the vehicles were not aware of the channel status that led to inaccurate estimation of the channel access. Our
models are an extension of models, taking into account the freezing of back-off timer and short retry limit in
order to accommodate the legacy specifications and to obtain accurate results of the packet delivery ratio.
3. THE ANALYTICAL MODEL OF THE HER-MAC PROTOCOL
We proposed 1-D and 2-D Markovian models for safety and service applications respectively, to
analyze and evaluate the performance of HER-MAC protocol in terms of packet delivery ratio. Our proposed
models are an extension of model, taking into account the freezing of back-off timer for both models, and
also the back-off stages along with a short retry limit in our service applications model in order to meet the
IEEE 802.11p specifications. We assumed non-saturated conditions by adding state to the models to
represent the empty queues in the MAC layer when no more packets are available in the buffer for
transmission. In the analytical model, the CCH is divided into two parts: reservation period (RP) and
contention period (TP) based on the HER-MAC protocol, more details refer to [21]. In order to transmit
safety packets in HER-MAC protocol, two access methods are used. Time division multiple access (TDMA)
is the first access method along with retransmission mechanism used to broadcast the safety packets. On the
other hand, Distributed Coordination Function (DCF) based on CSMA/CA technique with binary slotted
exponential back-off is used as the second access method, more details refer to [21]. Since the dissemination
of safety packets are in broadcast mode, the binary exponential back-off is disabled, and the vehicles will not
send any acknowledgement (ACK) for the received safety packets. Thus, the sender will not discover the
failure of safety packets and there is no retransmission. According to the HER-MAC protocol, on the CCH,
the packets transmissions are divided into two categories: safety packet and WAVE Service
Announcement/Request for Service (WSA/RES) packet transmission. In the models, and denote the
packets arrival rate of both safety and service traffics respectively. Packets arrival rate satisfies Poisson
distribution. There are vehicles in the network competing for the medium access. In the HER-MAC
protocol, there are two queues with the same traffic arrival rate during the CCHI: CCHI and SCHI queues.
Thus, the traffic arrival rate of safety and WSA/RES packets at each vehicle are and respectively, for
more details refer to.
3.1. Case 1: Probability of Frame Transmission uses TDMA access method
In this subsection, the TDMA access method along with retransmission mechanism is used to
transmit a safety packet. All vehicles broadcast a SAFE packet to reserve the Emergency Slots (EmgSlots) on
reservation period. Once a vehicle reserved an EmgSlot successfully, it is able to broadcast a safety packet
during its reserved EmgSlots without any collision. The main field of each safety packet is divided into five
fields which include: an ID, a serviced slot, the IDs of neighbor nodes, the time slot of each neighbor node,
safe applications, as shown in Figure 4. The vehicle may occupy an EmgSlot successfully when it transmits a
safety packet on the reservation period and all neighbor vehicles confirm an ID and serviced EmgSlot of this
contended vehicle. Otherwise, a vehicle fails to occupy an EmgSlot successfully. Thus, if the vehicles could
not reserve the EmgSlots successfully, they should broadcast HELLO packets in the next SI to reserve the
Emgslots. In this study, we assumed each vehicle has only a safety application packet to broadcast in the
CCHI. Since safety packet broadcast and HELLO packet broadcast use the same mechanism to be
disseminated, we used the same Markov chain model to analyze both safety and HELLO packets broadcast,
as shown in Figure 5. We assumed the payload of both safety and HELLO packets have the same length.
ID SerSlot IDs of neighbor nodes
The time slot used by each
neighbor node
Safety applications
Figure 4. Safety Packet Frame
However, the unidimensional process ( ) of safety and HELLO packets are analyzed with a
discrete-time Markov chain in which the channel status changes. The term ( ) describes the random
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variable representing the value of the back-off timer ( ) for a given station at slot time .
Since the transmission of safety and HELLO packets are in broadcast mode, and have the highest priority, the
back-off stages are disabled. The state of this process is denoted by ( ). From Figure 5 of state transition
diagram of Markov chain for the safety process, the non-null transition probabilities are written as follows:
{
( )
( )
( )
(1)
Here are the non-null transition probabilities to describe the unavailability of packets transmission in
the buffer, hence changing the station into idle ( ) state after a successful transmission.
{
( )
( )
( )
(2)
Figure 5. Markov Chain Model of The Safety Applications
Let = * ( ) +be the stationary distribution of the Markov chain. Given that,
( ), where is the contention window of safety process. From the Markov chain, the stationary
distribution of and are calculated as follows:
( ) ( ) (3)
(4)
(5)
Therefore, by using the normalization condition for stationary distribution, we have
∑
∑
∑
1-
/
/
1-
0
1-1- 1-
2 -2 -11
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(6)
Hence, from (6), we obtain (7)
( )
( ) ( )
(7)
Now we can express the probability that a vehicle can transmit safety or HELLO packet in an arbitrary
slot time. The vehicle can only transmit when the back-off time counter is zero ( ).
( )
( ) ( )
(8)
The collision probability when more than one vehicle transmits a packet at the same slot time is
given by
( ) (9)
We notice that the value of depends on the conditional collision probability and probability of
at least one safety or HELLO packet in buffer . The collision probability occurs when more than one
vehicle is transmitting in the same time slot. From equations (8) and (9), we can solve the unknowns
by using numerical techniques in order to calculate the packet delivery ratio (PDR). Note that
and . The PDR of the safety applications in the legacy is
( ) (10)
During the safety or HELLO packet interval, let denote the probability of
an idle channel, the probability of a busy channel, the probably of successful transmission, and the
probability of collision transmission respectively, which are computed with
{
( )
( )
( )
(11)
Let , , σ, and δ are the average times that the channel is sensed busy due to a successful
transmission of safety or HELLO packet, and the average time that the channel is sensed busy by each
vehicle during a collision because of the safety or HELLO packet, the duration of the slot time, and the
propagation delay respectively.
(12)
The average duration of the logical slot that might be spent for each process (successful
transmission, collision or idle) in the system is given by
( ) ( ) ( ) (13)
The traffic arrival rate for safety applications in VANETs satisfy the Poisson distribution, which is
denoted by , while M/G/1 is the queue of each station. The load equation of probability of at least one
safety packet in the buffer is given by
(14)
As mentioned earlier, based on the HER-MAC protocol, in case vehicles couldn’t reserve the
EmgSlots successfully, they will broadcast HELLO packets in the next SI to reserve Emgslots. HER-MAC
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protocol exploits the whole SI (100ms) to transmit safety and HELLO packets concurrently, while the legacy
takes half of SI (50ms) to transmit safety packets. Thus, after 50ms, in HER-MAC protocol, the average
number of vehicle that fails to transmit HELLO packets successfully is . By substituting for n
in equation (9), we can solve the unknowns The PDR of safety packet in the second SI
is ( ) . The PDR of HELLO packets of HER-MAC protocol through the SI (100 ms) is
defined by
( )( ) (15)
3.2. Case 2: Probability of Frame Transmission Uses CSMA/CA Access Method
Typically the transmission of safety applications are in broadcast mode and independent of
transmission of service application, thus, we keep using the Markov model in case 1 to analyze the
transmission of safety applications. In order to analyze the probability of frame transmission of service
applications (WSA/RES), let ( ) be the random variable representing the back-off stage ( ) for
a given station at slot time . Note that, ( ) is the random variable representing the value of the back-off
timer ( ) for a given station at slot time . Typically, the maximum value of the back-off
timer relies on the back-off stage. Hence, these random variables are not independent.
{ (16)
is the initial size of the contention window of service application, ( ) while
is the maximum number in which the contention window can be doubled, ( ). We
used and the maximum value of back-off stages is denoted by . Let denotes the probability of
collision that more than one vehicle transmits in the same slot time simultaneously, and be the probability
of at least one new WSA/RES packet in the buffer.
Nevertheless, the bi-dimensional ( ( ) ( )) processes for service applications are analyzed here
with a discrete-time Markov chain at which the channel state changes. The state of this process is denoted by
( ). Figure 6 exhibits the state transition diagram of Markov chain for the service process, and the non-null
transition probabilities are written as follows:
{
( )
( )
( )
( ) ( )
( )
(17)
Here are the non-null transition probabilities to describe the unavailability of packet transmissions in
the buffer which are redirected into idle ( ) state after successful transmission.
{
( ) ( )( )
( )
( )
( )
(18)
Let = * ( ) ( ) + be the stationary distribution of the Markov chain,
where ( ) ( ). First, note that
0 < i ≤ m
(19)
Due to the chain regularities, for each ( ), the stationary distribution
of and is calculated as follows:
( )
{
( ) ∑
(20)
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Or
( )
(21)
( )( ) ∑ ( ) ( ) (22)
Mathematically solving (22), we obtain (23)
(23)
Figure 6. Markov Chain Model of the Service Applications
Thereby, the normalization condition of stationary distribution is used which is elaborated as the
following:
∑ ∑
∑ ∑ ∑
∑ ∑ ∑
( )
∑ ∑
∑ ∑
∑
( )
[∑ ( ) ∑ ] (24)
Mathematically solving (24), we obtain (25)
p / ,
/ ,
/ , ′
/ ,1
i-1, 0
p / ,
(1- )(1- )
(1- )
(1- )
(1- )
(1- )(1-
)
(1- )(1- )
1-
Idle
/
,0
(1-
)/ ,0
1-
0, 0
1-1- 1-
0, 2 0, ,0-
2
0, ,0-
1
0, 1
p /
,
m, 0
1-1- 1-
m, , -
2
m, , -
1
m, 2m, 1
i, 0
1-1- 1-
i, , -
2
i, 2i, 1 i, , -1
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{
( ) ( )
( ) ( )
(25)
where
( ) ( ) ( )( ( ) )
( ) ( )( ) (26)
( ) ( ) ( )( ( ) ) ( )
( ) ( ) ( )( ) (27)
We can now express the probability that a node can transmit service packet in a randomly chosen
slot time. The vehicle can only transmit when the back-off time counter is zero ( ) regardless of the back-
off stage.
∑ (28)
We notice that the values of depend on the conditional collision probability and the
probability of at least one WSA/RES packet in the buffer respectively. The collision probability occurs
when more than one vehicle is transmitting in the same time slot simultaneously.
The collision probabilities, of safety and service applications are defined as follows:
( ) ( ) (29)
( ) ( ) (30)
From equations (8), (28), (29), and (30), we can solve the unknown by using numerical
techniques. Let denote the probability of an idle and busy channel respectively during a given
slot. The probably of successful transmission for safety and service packets are denoted respectively
by . The collision transmission could happen with safety packet only , service packet only , or by
both . Therefore, we have
{
( ) ( )
( ) ( )
( ) ( )
( ) ( )
( ) ( ( ) ( ) )
( ) ( ( ) ( ) )
(31)
In general, the system in VANETs can be either in broadcast mode or ACK with RTS/CTS access
mechanism for safety and service applications transmission respectively. Thus, let
be the transmission time of a WSA, RES, ACK, and safety application
respectively, assuming that and . and are the duration time of SIFS
and DIFS respectively. The duration of a free slot time, the average time that the channel is sensed busy due
to a successful reservation, and the average time that the channel is sensed busy by each node during a
transmission collision are denoted respectively by .
{
(32)
The average duration of the logical slot that might be spent for each process (successful
transmission, collision or idle) in the system is given by
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( ) ( ) (33)
The traffic arrival rate for safety and service applications in VANETs satisfy Poisson distribution
denoted, which are by , in which the traffic arrival rate for service applications are exponentially
distributed, while M/G/1 is the queue of each station. The load equations of probability of at least one safety
or WSA/RES packet in the buffer are given respectively by
(34)
(35)
The packet delivery ratio (PDR) of the safety packet in the legacy is derived as the probability of
having a successful transmission, given that the slot is busy
( ) ( ) (36)
Based on the HER-MAC protocol, the safety packets are transmitted twice and the successful
transmission during CCHI is the same with the legacy as in (36). HER-MAC protocol also utilizes the CCH
during the SCHI to transmit safety and WSA/RES packets. The PDR of the safety applications is also similar
with the legacy. Thereby, the PDR of safety application in HER-MAC protocol is computed as
( ) (37)
4. PERFORMANCE EVALUATION MODEL
In the following sections, we discuss and compare the analysis of the simulation and numerical
results of our Markov models and the previous models by [22], to gain better understanding on the behavior
of broadcasting safety applications in HER-MAC protocol in VANETs. We validated the simulation results
of our models with network simulator (ns-2) version 2.34, while the numerical results were obtained using
Matlab. The data rate R for MAC layer channel was set to 6 Mbps for all vehicles. The traffic arrival rate of
safety and HELLO packets was fixed at 200 packets/second (pkts/sec), while the traffic arrival rate of service
applications was 50 pkts/sec, more parameter values are summarized in Table 1. The performance evaluation
of the proposed and existing models in terms of PDR with respect to the number of vehicles n and contention
window is scrutinized in this paper.
Safety applications are a part of VANETs applications, thus, in this paper we examined the behavior
of broadcasting the safety packets according to HER-MAC protocol. As the safety applications are in
broadcast mode, the ACK mechanism and retransmission are disabled. In case 1, each vehicle has to reserve
an EmgSlot in order to broadcast a safety packet during its reserved EmgSlots without any collision. If a
vehicle fails to reserve the EmgSlots successfully and it has safety packets to broadcast, a vehicle should try
to broadcast HELLO packets in the next SI to reserve an Emgslot based on HER-MAC protocol. Figure 7
and 8 illustrate the performance of the proposed and existing model in terms of PDR with respect to different
number of vehicles, n and contention window . It is clear from Figure 7 that the PDR of the network is
strongly affected by the number of vehicles and contention window . Accordingly, it is notable from
Figure 7 that along with the increase in vehicles, the PDR of the network decreases for both proposed and
existing model [22]. This is because of the inversely proportional relationship between the PDR and number
of vehicles, thus it is believed that the collision probability at the same time slot increases with the increase of
vehicles in the network. This then leads to a lower value of PDR. Between our proposed model derived in
this study and the model by [22], Figure 7 clearly marks high values of PDR from our models with
percentage increase of 121%. This is due to the freezing of the back-off timer that has been taken into
consideration in our model, which provides an accurate estimation of the channel access and yields more
precise results of the PDR. On the other hand, Figure 8 offers the effect of various initial contention window
sizes on the values of PDR. We can see from the Figure 8 that along with increasing , the values of
PDR on the network increase as well for both proposed and existing model [22]. This is because of the longer
interval backoff time among vehicles for transmitting a safety packet, which leads to the lower probability of
choosing the same timeslot value by more than one vehicle. Figure 8 also displays that higher values of PDR
are achieved by our proposed model derived in this paper with percentage increase of 53.1% as compared to
the existing model [22].
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Table 1. Parameters Values
Parameters Value
Channel capacity 6 Mbps
Safety application 100 bytes
WSA 100 bytes
HELLO 100 bytes
RES 14 bytes
ACK 14 bytes
SIFS 16 µs
Slot time σ 9 µs
DIFS 34 µs
Propagation delay δ 1µs
Number of SerSlots M 5
200 pkts/sec
50 pkts/sec
Minimum 8
Minimum 16
Maximum Retry limit 5
Figure 7. Packet Delivery Ratio of Safety Applications vs Number of Vehicles
Figure 8. Packet Delivery Ratio of Safety Applications vs Contention Window ( )
In case 2, according to HER-MAC protocol, the safety and WSA/RES packets are transmitted
simultaneously in the second half of the SI (50 ms). Figures 9 and 10 are the same as in case 1, the PDR of
the network is affected by the number of vehicles and contention window sizes. Since HER-MAC protocol
utilizes this interval to transmit both safety and WSA/RES packets concurrently, by increasing the number of
vehicles, probability of choosing the same timeslot value by more than one vehicle is high, which causes
higher collision among vehicles and lower PDR in the network compared to case 1. Between the proposed
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models derived in this study and the model by [22], Figure 9 and 10 clearly mark high values of PDR from
our models with percentage increase of 96.2% and 57% respectively. This is due to the freezing of the back-
off timer and the frame retry limit of service application that were taken into consideration in our models
which provides an accurate estimation of the channel access, and yields more precise results of the PDR.
Figure 9. Packet Delivery Ratio of Safety Applications vs Number of Vehicles
Figure 10. Packet Delivery Ratio of safety applications vs Contention Window ( )
5. CONCLUSION
In this paper, we present an improved 1-D and 2-D Markov chain models for both safety and non-
safety applications concurrently, to analyze and evaluate the performance of HER-MAC protocol under non-
saturated conditions, in which a buffer was added to hold the packets during traffic arrival when the channel
is busy. Backoff freezing along with short retry limit were considered in our models to accommodate the
IEEE 802.11p specifications to obtain an accurate system packet delivery ratio. The models’ performance
was evaluated based on TDMA and CSMA/AC access methods. The packet delivery ratio was the only
metric chosen to evaluate the models’ performance under different number of vehicles and contention
window sizes. The simulation results have validated the analytical results of our models. The results show
that our models significantly outperform the existing model in terms of the packet delivery ratio.
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